1. Field of the Invention
The present invention relates to a running machine which is usually used indoors for exercise or medical treatment.
2. Description of the Related Art
This type of running machine is, for example, described in a patent document 1 (Japanese Unexamined Laid-open Patent Publication No. 2002-85586) which the applicant previously filed, as shown in FIG. 9. This running machine is a slim type for easy getting on it, and thus the elderly people or the disabled can easily use it. Further, the machine is constructed to give a shock to a user as little as possible even if he or she falls down to a ground surface during running/walking.
As shown in FIG. 9, the running machine comprises, a bedplate 1 having side frames (not shown) separated from each other and being contacted to a ground surface; an endless belt 2 mounted between the side frames of the bedplate 1 and bent down at its ends; a supporting plate 3 bridged between the side frames of the bedplate 1, inserted between an upper portion and a lower portion of the endless belt 2 and coming into a sliding-contact with the upper portion of the endless belt 2 for supporting the same; a rotary roller 4 provided in an inner portion of one bent part of the endless belt 2 for circulatingly moving the endless belt 2; a sliding contact member 5 mounted at one end of the supporting plate 3 in an inner portion of the other bent part of the endless belt 2 and guiding the sliding-contact movement of the endless belt 2; a driving unit 6 consisting of an electric motor 6a and a belt transmission 6b for rotating and driving the rotary roller 4; and a tension roller 7 for depressing the upper portion of the endless belt 2 toward the lower portion, thereby making a distance L between the upper portion and the lower portion smaller than a diameter D of the rotary roller 4.
With such a constitution, since the upper portion of the endless belt 2 is depressed toward the lower portion by the tension roller 7 and thus the distance L between the upper portion and the lower portion becomes smaller than the diameter D of the rotary roller 4, it is possible to make a height H from a ground surface G to a running/walking surface of the endless belt 2 as small as possible without reducing an outer diameter of the rotary roller 4.
The reason why the sliding contact member 5 sliding-contact with the endless belt 2, rather than the rotary roller, is mounted at the end of the supporting plate 3 is as follows. Since the height H from the ground surface G to the running/walking surface of the endless belt 2 is small, if the rotary roller is used instead of the sliding contact member 5, a shaft or a bearing for the roller is required. Thus, it becomes structurally difficult to mount a roller having a corresponding roller diameter. Further, even if the roller having a corresponding diameter can be mounted, its strength is weak because the diameter of the roller is small. In addition, because a substantial tensile force is applied to the endless belt 2, a shake or torsion occurs in the roller and the endless belt 2 cannot smoothly slide and thus immediately stops, or the endless belt 2 rolls from side to side and thus contacts the bedplate resulting in damage and mechanical troubles.
In using the above running machine, a runner/walker gets on the endless belt 2 from the other bent part of the endless belt 2. At this time, since the height H from the ground surface G to the running/walking surface of the endless belt 2 is very small, it is easy to get on the endless belt 2. In this condition, the endless belt 2 is circulatingly moved, and the runner/walker walks or runs on the running/walking surface of the upper portion according to the moving speed of the endless belt 2. During this walking/running, even if the runner/walker unwantedly falls down from the other bent part of the endless belt 2, the shock can be reduced since the height from the ground surface G to the running/walking surface of the endless belt 2 is very small. When the runner/walker wants to stop running/walking, he or she gets down from the other bent part of the endless belt 2. Likewise, since the height H from the ground surface G to the running/walking surface of the endless belt 2 is very small, it is easy to get down from the endless belt.
In the conventional running machines, it is a slim type and thus sliding contact member 5 for guiding the endless belt 2 so as to slidingly move in contact with it is mounted at the end of the supporting plate 3. However, since a substantial tensile force is applied to the endless belt 2, frictional resistance increases and thus durability of the endless belt 2 is heavily affected. Meanwhile, if frictional force is reduced by decreasing the tension of the endless belt 2 against the sliding contact member 5 to solve such problems, a slip out of the rotary roller 4 occurs and thus the endless belt 2 is not moved smoothly.